package vip.zhenzicheng.algorithm.leetcode.sql;

/**
 * <a href="https://leetcode.cn/problems/find-customer-referee/">寻找用户推荐人 [简单]</a>
 *
 * @author zhenzicheng
 * @date 2022-06-30 14:37
 */
public class FindCustomerReferee_584 {

  /**
   * 使用库函数转换为0
   */
  String sql1 = "select name from customer where IFNULL(referee_id, 0) <> 2";
  /**
   * 重点在于：= 或 ！= 只能判断基本数据类型 is 关键字只能判断null
   */
  String sql2 = "select name from customer where referee_id != 2 or referee_id is null;";
}
